[NVPTX] Cleanups

- Remove dead code in InstPrinter
- Capitalization and improve Table comments
- Update fence->membar lowering

Author: gonzalobg

llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXInstPrinter.cpp

@@ -256,18 +256,6 @@ void NVPTXInstPrinter::printLdStCode(const MCInst *MI, int OpNum,
         report_fatal_error(OS.str());
         break;
       }
-    } else if (!strcmp(Modifier, "sc")) {
-      auto Ordering =
-          NVPTX::Ordering(static_cast<NVPTX::OrderingUnderlyingType>(Imm));
-      switch (Ordering) {
-        // TODO: refactor fence insertion in ISelDagToDag instead of here
-        // as part of implementing atomicrmw seq_cst.
-      case NVPTX::Ordering::SequentiallyConsistent:
-        O << "fence.sc.sys;\n\t";
-        break;
-      default:
-        break;
-      }
     } else if (!strcmp(Modifier, "addsp")) {
       switch (Imm) {
       case NVPTX::PTXLdStInstCode::GLOBAL:

llvm/lib/Target/NVPTX/NVPTXISelDAGToDAG.cpp

@@ -717,10 +717,10 @@ static unsigned int getCodeAddrSpace(MemSDNode *N) {
 struct OperationOrderings {
   NVPTX::OrderingUnderlyingType InstrOrdering;
   NVPTX::OrderingUnderlyingType FenceOrdering;
-  OperationOrderings(NVPTX::Ordering o = NVPTX::Ordering::NotAtomic,
-                     NVPTX::Ordering f = NVPTX::Ordering::NotAtomic)
-      : InstrOrdering(static_cast<NVPTX::OrderingUnderlyingType>(o)),
-        FenceOrdering(static_cast<NVPTX::OrderingUnderlyingType>(f)) {}
+  OperationOrderings(NVPTX::Ordering O = NVPTX::Ordering::NotAtomic,
+                     NVPTX::Ordering F = NVPTX::Ordering::NotAtomic)
+      : InstrOrdering(static_cast<NVPTX::OrderingUnderlyingType>(O)),
+        FenceOrdering(static_cast<NVPTX::OrderingUnderlyingType>(F)) {}
 };
 
 static OperationOrderings
@@ -734,6 +734,8 @@ getOperationOrderings(MemSDNode *N, const NVPTXSubtarget *Subtarget) {
   // clang-format off
 
   // Lowering for Load/Store Operations (note: AcquireRelease Loads or Stores error).
+  // Note: uses of Relaxed in the Atomic column of this table refer
+  // to LLVM AtomicOrdering::Monotonic.
   //
   // | Atomic  | Volatile | Statespace         | PTX sm_60- | PTX sm_70+                   |
   // |---------|----------|--------------------|------------|------------------------------|
@@ -1153,7 +1155,7 @@ bool NVPTXDAGToDAGISel::tryLoad(SDNode *N) {
   case NVPTX::Ordering::SequentiallyConsistent: {
     unsigned Op = Subtarget->hasMemoryOrdering()
                       ? NVPTX::atomic_thread_fence_seq_cst_sys
-                      : NVPTX::atomic_thread_fence_seq_cst_sys_membar;
+                      : NVPTX::INT_MEMBAR_SYS;
     Chain = SDValue(CurDAG->getMachineNode(Op, dl, MVT::Other, Chain), 0);
     break;
   }
@@ -1316,7 +1318,7 @@ bool NVPTXDAGToDAGISel::tryLoadVector(SDNode *N) {
   case NVPTX::Ordering::SequentiallyConsistent: {
     unsigned Op = Subtarget->hasMemoryOrdering()
                       ? NVPTX::atomic_thread_fence_seq_cst_sys
-                      : NVPTX::atomic_thread_fence_seq_cst_sys_membar;
+                      : NVPTX::INT_MEMBAR_SYS;
     Chain = SDValue(CurDAG->getMachineNode(Op, DL, MVT::Other, Chain), 0);
     break;
   }
@@ -1988,7 +1990,7 @@ bool NVPTXDAGToDAGISel::tryStore(SDNode *N) {
   case NVPTX::Ordering::SequentiallyConsistent: {
     unsigned Op = Subtarget->hasMemoryOrdering()
                       ? NVPTX::atomic_thread_fence_seq_cst_sys
-                      : NVPTX::atomic_thread_fence_seq_cst_sys_membar;
+                      : NVPTX::INT_MEMBAR_SYS;
     Chain = SDValue(CurDAG->getMachineNode(Op, dl, MVT::Other, Chain), 0);
     break;
   }
@@ -2148,7 +2150,7 @@ bool NVPTXDAGToDAGISel::tryStoreVector(SDNode *N) {
   case NVPTX::Ordering::SequentiallyConsistent: {
     unsigned Op = Subtarget->hasMemoryOrdering()
                       ? NVPTX::atomic_thread_fence_seq_cst_sys
-                      : NVPTX::atomic_thread_fence_seq_cst_sys_membar;
+                      : NVPTX::INT_MEMBAR_SYS;
     Chain = SDValue(CurDAG->getMachineNode(Op, DL, MVT::Other, Chain), 0);
     break;
   }